M. W. F. TWEEDIE Sesarma (Chiromantes) dussumieri H. Milne-Edwards. 1853. Sesarma dussumieri H. Milne-Edwards, Ann. Sci. Nat. Zool., (3), xx, p. 185 (Bombay). 1917. Sesarma (Chiromantes) dussumieri Tesch, Zool. Meded., Leiden, iii, p. 146. Material.—Specimens from Pulau Pawai, Pulau Bukom and Pulau Senang, Islands near Singapore, 1934. Sesarma (Chiromantes) eumolpe de Man. 1895. Sesarma (Perisesarma) eumolpe de Man, Zool. Jahrb. Syst., ix, p. 208; x (1898) pi. 31. fig. 38 (Penang). 1917. Sesarma (Chiromantes) eumolpe, Tesch, Zool. Meded., Leiden, iii, p. 150. Material.—Numerous specimens from Singapore (River Jurong) and neighbouring islands (Pulau Bukom, Pulau Senang), the Johore Strait and Port Swettenham, Selangor, 1934. Sesarma (Chiromantes) onychophora de Man. 1888. Sesarma livida de Man (nee A. Milne-Edwards), Journ. Linn. Soc. London, xxii, p. 179 (Mergui Archipelago). 1895. Sesarma (Perisesarma) onychophora de Man, Zool. Jahrb. Syst., ix, p. 214; x (1898) pi. 31, fig. 39 (Penang, Atjeh and Pontianak). Material.—Numerous specimens from Port Swettenham, Selangor, 1934; two males and a female from Butterworth, Province Wellesley (the point on the mainland opposite Penang), collected by C. Dover, 1927. At Port Swettenham this is by far the commonest species of Sesarma; and yet among the hundreds of specimens of the genus collected by the staff of this museum in Singapore not one of S. onychophora has occured, although Lanchester records the species from Singapore. Sesarma (Chiromantes) bidens indica de Man. 1902. Sesarma (Perisesarma) bidens var indica de Man, Abhandl. Senckenb. Gesellsch., xxv, p. 541 (Amboina). 1917. Sesarma (Chiromantes) bidens indica, Tesch, Zool. Meded., Leiden, iii, p. 135. Material.—Numerous specimens from Singapore and the neighbouring islands. Sesarma (Chiromantes) faseiata Lanchester. Plate XV, fig. 3. 1900. Sesarma [Parasesarmal faseiata Lanchester, Proc. Zool. Soc. London, 1900, p. 758. 1909. Sesarma (Chiromantes) siamense Rathbun, Proc. Biol. Soc. Wash., xxii, p. 109. 1910. Sesarma (Chiromantes) siamense, Rathbun, K. Dansk. Vid. Selsk. Skr., vii Raekke, Afd. 5 No. 4, p. 328. Material.—A good series from Singapore (Jurong River), the Johore Straits and Pulau Senang, near Singapore; a male and two females from Port Swettenham, Selangor. [ 66 ] BULL. RAFFLES CRABS OF THE FAMILY GRAPSID^S A specimen of this material was compared with the type of S. svamense Rathbun in the Copenhagen Museum by Dr. K. Stephensen and pronounced to be identical. With Dr. Rathbun's description (l.c.) the present series is in complete agreement except that the meri of the legs do not carry a sharp anterior subdistal spine, but only an angulation with a stiff moveable bristle. At the same time Dr. Isabella Gordon was kind enough to compare Lanchester's types of S. fasciata in the British Museum with Dr. Rathbun's description of S. siamense and as a result of this comparison expressed an opinion that the two are synonymous. When Lanchester in his text referred this species to the subgenus Parasesarma he did so with the reservation that one of the females had "indications of a tooth behind the orbital angle". In the present series this feature shows considerable variation. The epibranchial tooth is always low and obtuse, often obscure, and in one adult male, scarcely indicated. Lanchester mentions a large triangular tooth at the inner angle of the carpus, but his figure (I.e. PI. 47, fig. 12a, 12b) shows little more than the "blunt angulation" described by Dr. Rathbun. His description of the ornamentation of the upper margin of the moveable finger is inaccurate. To the naked eye or to a low powered hand lens the characteristic spines might, in a small specimen, appear as "obscure, low tubercles", but under a magnification of about 20 diameters they are always distinct. The coloration of the present specimens is just as described for S. fasciata. Subgenus Sarmatium Dana 1851. Tesch (1917) treated Sarmatium as a full genus. More recently de Man1 has expressed the opinion that it should be regarded as a subgenus of Sesarma "characterized especially by the general outer appearance and the characters of the terminal and othe penultimate segment of the abdomen both in the male and in the female". If de Mans ruling, together with his characterization of the subgenus, are accepted, Sesarma (Sesarma) smithii H.M.-E. must, in my opinion, be transferred to Sarmatium. Sesarma (Sarmatium) crassum (Dana). 1851. Sarmatium crassum Dana, Proc. Ac. Nat. Sci. Philad., 1851, p. 251 (Upolu, Samoa). 1917. Sarmatium crassum, Tesch, Zool. Meded., Leiden, p. 215. 1 de Man, Vidensk. Medd. fra Dansk. Naturh. Foren., 87 (1929), p. 118. Mus. 12, 1936. [ 67 ] M. W. F. TWEEDIE Material.—Specimens from Singapore (River Jurong), the Johore Straits and Port Swettenham, Selangor, 1934. Sesarma (Sarmatium) smithii H. Milne-Edwards. 1853. Sesarma smithii H. Milne-Edwards, Arch. Mus. Paris, vii, p. 149 (South Africa). 1917. Sesarma (Sesarma s. s.) smithii, Tesch, Zool. Meded., Leiden, iii, p. 199. Material.—A single large male of this widely distributed species, labelled "Singapore" without any record of date or collector. Genus Clistocoeloma1 A. Milne-Edwards. Clistocoeloma merguiense de Man. Plate XV, fig. 4. 1888. Clistocoeloma merguiense de Man, Journ. Linn. Soc. London, xxii, p. 195. (Mergui Archipelago). 1917. Clistocoeloma merguiense, Tescn, Zool. Meded., Leiden, iii, p. 222. Material.—Numerous specimens from Singapore and neigh- boring islands, the Johore Strait and Port Swettenham, Selangor; One male from the Nicobar Islands, presented by the Indian Museum. Specimens from Singapore were compared with well authenticated material by Prof. Dr. H. Balss and by Dr. B. N. Chopra, and both confirmed the identity of the Malayan species with C. merguiense. Dr. Chopra pointed out certain minor differences between the Malayan specimens and those in the Indian Museum. The most important is that in the latter there is always an appreciable gap between the internal subocular lobe and the edge of the front, so that the antennae are not completely excluded from the orbits. In the specimens in the Indian Museum this gap is either very small or non-existent, a feature that has been regarded as of importance in separating the genus from Sesarma. Further, the second tooth on the antero-lateral border is slightly smaller than the others in the Malayan examples, whereas in the Indian specimens all three teeth are generally equal, and the emargination of the front is rather shallower in the Malayan specimens. There are also some slight differences in the propor- tions of the chelipeds. The number of tubercles on the dactylus of the male is rather variable, ranging in fully adult specimens from 14 to as many as 19; in large females about 12 or 13 tubercles are present. i- Dr. B. N. Chopra tells me, in litt, that S. (S.) lanata Alcock is a true Sesarma and not a Clistocoeloma, as suggested by Tesch, Zool. Meded., Leiden, iii, 1917, p. 239 (footnote). [ 68 ] BULL. RAFFLES CRABS OF THE FAMILY GRAPSIDJE Genus Metaplax H. Milne-Edwards. Until recently only one species, M. elegans de Man, of this genus was known to occur in the Malaysian subregion. In 1933 M. longipes Stimpson was recorded by Balss from Lombok, which lies just outside the limits of "Malaysia", and in the present collection are specimens of M. crenulatus (Gerstaecker) and M. sheni from the Malayan coasts. Metaplax elegans de Man. 1888. Metaplax elegans de Man, Journ. Linn. Soc. London, xxii, p. 164, pi. xi, fig. 4-6 (Mergui Archipelago). 1892. Metaplax erassvpes de Man, Weber's Zool. Erg. Reise Neiderl. Ost-Indien, ii, p. 325, pi. xix, fig. 12. 1895. Metaplax elegans, de Man, Zool. Jahrb. Syst., viii, p. 596. Material.—Numerous specimens from Singapore (River Jurong) and Port Swettenham, Selangor, 1934. Metaplax crenulata (Gerstaecker). 1856. Rhaconotus crenulatus Gerstaecker, Arch. Naturgesch., Jahrg., xxi, p. 142, pi. v, fig. 5. 1888. Metaplax crenulatus, de Man, Journ. Linn. Soc. London, xxii, p. 156 (Mergui Archipelago). 1918. Metaplax crenulata, Tesch, "Siboga"-Exped., xxxixc, p. 116. Material.—One large male and juvenile individuals from Port Swettenham, Selangor, 1934. This extension of the range of M. crenulata into the Malay- sian region is of parochial rather than zoo-geographical interest, as the west coast of the Malay Peninsula is in reality no more than the southern extension of the eastern shore of the Bay of Bengal, which is the type locality of the species. Metaplax sheni Gordon. Plate XV. fig. 5. 1930. Metaplax sheni Gordon, Ann. Mag. Nat. Hist., Ser. 10, vi, p. 525 (Amoy, (China). 1931. Metaplax sheni, Gordon, Journ. Linn. Soc. Zool., xxxvii, p. 553. Material.—Two males from Pulau Senang, an island near Singapore, and the river Jurong, Singapore. Subfamily PLAGUSIIN®. Genus Plagusia Latreille. Plagusia depressa tuberculata Lam. 1801. Plagusia tuberculata Lamarck, Hist. Nat. Anim. s. V. p. 246. 1906. Plagusia depressa tuberculata, Laurie, Rep. Pearl Oyster Fish. Ceylon, v, pp. 429-30. 1918. Plagusia depressa tuberculata, Tesch, "Siboga"-Exped., xxxixc, p. 129. Material.—One male and seven females from Horsburgh Lighthouse, off the south-east point of Johore, 1934. Mus. 12, 1936. [ 69 ] £ M. W. P. TWEEDIE Genus Percnon Gistel. Percnon demani Ward. 1902. Leiolophm abbreviate de Man (nec. Dana), Abhandl. Senckenb. Gesellsch, xxv, p. 544 (Ternate). 1934. Percnon demani Ward, Bull. Raffles Mus., ix, p. 24 (Christmas Island, Indian Ocean). Material.—One adult male and five juveniles from Christmas Island, Indian Ocean, 1932. These specimens were among these examined and figured by Melbourne Ward (l.c.). EXPLANATION OP PLATES PLATE XIV. Fig. 1. Pachygrapsus quadratus, type. Fig. 2. Metopograpsus latifrons, male. Fig. 3. Sesarma palawanensis, male. Fig. 4. S. palawanensis, male; frontal view showing chelae. PLATE XV. Fig. 1. Sesarma gemmifera, male. Fig. 2. Sesarma rutilimana, male. Fig. 3. Sesarma faseiata, male. Fig. 4. Clistocoeloma merguiense, male. Fig. 5. Metaplax sheni, male. Note on Paratelphusa (Liotelphusa) kadamaiana By M.